Calorimeter

Challenge: To design a thermistor-based thermometer and calorimeter for determination of the mass of an ice cube.

Parameters: Your device will incorporate a thermistor circuit that you will calibrate for temperature determination. It should be an insulated cup that can hold water and an added regular-sized ice cube. You need to know the mass of your calorimeter and can measure the amount of water you add by difference. You will then determine the initial temperature with your thermistor circuit and MUST RETURN the scale to the cupboard before the competition. Mr. J will find the mass of an ice cube (assume a temperature of 0.0 °C) immediately before dropping it into your device. From the change in temperature caused by the melting ice, you must calculate the mass of ice added.

Scoring: Your score will be determined by your ability to estimate the mass of the ice cube added to your device as follows:

Score = | % difference from accepted mass |

Lowest score will earn the highest rank.

Physics: A known mass of water in a closed system will lose energy to the phase change occurring as ice melts. It will also lose energy to the ice-cold water as the two volumes of water reach equilibrium temperature. In other words, you need to use both heat formulae! The heat capacity of water (C_H2O = 4186 J/kg°C), and the latent heat of fusion coefficient of ice (L_f = 334 kJ/kg) are necessary for this calculation.

Extensions: The materials that make up your device have mass and will change temperature, so your system is not really “closed” perfectly, and therefore has its own “heat capacity”. When choosing the mass of water you start with in your calorimeter, consider relative uncertainty. For example, a change of -3.5 °C ± 0.5 °C is more uncertain than a change of -8.5 °C ± 0.5 °C.

Help/Hints: Please give yourself lots of time to calibrate your thermistor and try out your calorimeter. The heat capacity factor mentioned above can be minimized by making your device smaller and lighter, with insulating materials. You can actually quantify this factor and therefore be able to get a more accurate answer for the mass of the ice.

Quiz Topics: OpenStax High School Physics: 11.1 - 11.3, 19.1 -19.3

OpenStax College Physics: 13.1, 14.1-14.7 (math .1-.3 only), 20.1 - 20.3